The neurochemical event which lead to the formation of a mature, functional synapse are not completely understood. This application proposes several approaches which may eventually lead to a better understanding of the development of synapses which use acetylcholine (ACh) in the ferret retina. Acetylcholine has been chosen because a number of advanced techniques are available to study all aspects of the cholinergic synapse. The retina was chosen because it is more accessible and readily understood than any other central nervous system (CNS) sensory tissue. The ferret CNS is ideal for these studies because the newborn ferret is Quite immature, allowing many salient events in CNS development to be studied postnatally. Studies under Specific Aim 1 will examine the development of choline acetyltransferase, the enzyme responsible for synthesizing ACh. Specific Aim 2 contains proposed work on the development of cholinergic receptors. In Specific Aim 3, experiments are proposed to study the development of acetylcholinesterase, the enzyme which degrades ACh at the synapse. Specific Aim 4 combines techniques selected from the previous studies to co-localize enzymes and receptors int he retina at each key point in development. Additional studies under Specific Aim 4 will combine techniques to study the development of retinal cells utilizing gamma- aminobutyric acid and acetylcholine as transmitters. Taken together, these Specific Aims are directed at defining the temporal sequence of appearance of neurochemical markers which are essential for maturation and functioning of cholinergic synapses, during development and into adulthood. The ultimate goal of he work is to more fully understand how the cholinergic and the cholinoceptive cell coordinate with each other during development of the visual system in order to manufacture and express the proteins necessary to produce a fully functional mature synapse. The proposed experiments, when completed, will increase our base of knowledge about the development of cholinergic synapses in the mammalian retina, and (by extension) in the nervous system as a whole. This, in turn, may allow us to better understand the deviations from normal events which lead to abnormal development, including certain types of mental retardation and visual impairment.